Microbial Utilization and Transformation of Humic Acids Extracted from Different Soils

Humic acids (HA) extracted from Chernozem (Haplic Phaeozem), Brown Earth (Cambic Umbrisol) and Podzol (Humic Podzol) were added as a supplemental source of nutrients, or as the sole sources of carbon and nitrogen to aerobic cultures of complex microbial communities indigenous to the same individual soils. Depending on nutrient conditions in the individual cultures and origin of HA, between 14 and 86 % of the added HA was utilized. The formation of microbial biomass was enhanced up to six fold in the full-strength nutrient media supplemented with humic acids but was strongly inhibited if HA served as the sole C source. HA preparations re-isolated from the microbial cultures exhibited elemental and structural changes characteristic for early diagenetic transformations of humic substances. These included an increase in carbon content, C:N ratio, infra-red absorption typical for aromatics, and a decrease in infra-red absorption associated with aliphatic acids, nitrogenous and carbohydrate-like substances.     

不同土壤腐殖酸对辛硫磷水解的影响

各种试验土壤腐殖酸的紫外吸收曲线相似,但吸收峰强度和E 465/E 665值差异较大,腐殖酸的腐殖化程度由大至小排序为：紫色潮土HA〉黄壤HA〉中性紫色土HA〉酸性紫色土HA,说明它们组成相似,结构和性质有差异。在此基础上,研究它们对辛硫磷水解的影响。结果表明,不同来源土壤腐殖酸均阻碍辛硫磷的水解,但它们的影响程度有明显的差异。腐殖酸溶液浓度越大,辛硫磷水解速率越慢,相同腐殖酸浓度下以腐殖化程度较高的紫色潮土的作用最大。初步说明辛硫磷的水解速率与土壤腐殖酸的浓度和腐殖化程度有关。     

土壤腐殖酸对毒死蜱水解的影响

土壤腐殖酸的VIS-UV光谱特征和E465/E665的测定结果表明,各种土壤腐殖酸的VIS-UV吸收曲线相似,但吸收峰强度和E465/E665差异较大,进而推得它们的腐殖化程度排序为:紫色潮土腐殖酸>中性紫色土腐殖酸>酸性紫色土腐殖酸>腐殖土腐殖酸,说明它们在组成上有共同的本性,但结构和性质差异较大。在此基础上,研究它们对毒死蜱水解的影响。结果表明,不同来源土壤腐殖酸均促进了毒死蜱的水解,但它们的影响程度有明显的差异。对于腐殖化程度最低的腐殖土腐殖酸,浓度为120mg L-1时,对毒死蜱水解的促进作用最大,而随着腐殖酸浓度的增大,促进作用却越来越弱;而对于其它三种样品,腐殖酸溶液对毒死蜱水解的促进作用随着腐殖酸浓度增大而加强,其中以腐殖化程度较低的酸性紫色土的促进作用较为明显。可见,毒死蜱的水解速率与土壤腐殖酸的浓度和腐殖化程度有关。其中,腐殖酸腐殖化程度的影响机理主要与腐殖酸的酸性和腐殖酸的吸附—催化作用有关,其具体作用机理有待于进一步从定性和定量方面去研究,以更好地指导毒死蜱农药的合理施用和污染土壤的修复。     

Characterization of Humic Acids in Mountainous Meadow Soils and Burozems of the Crimea Using 13C-NMR

Eurasian Soil Science - A comparative analysis of organic matter in the mountainous soils under the main plant communities of the Crimea was performed. The humus state of burozems and mountainous...     

不同浸提剂处理森林土壤溶解性有机碳含量比较

为了解亚热带森林土壤溶解性有机碳(DOC)的特征规律,采用培养离心的方法获取土壤溶液测得DOC含量,对比传统水溶性有机碳(WSOC)提取法间的差异。选取湖南大山冲森林公园保存完好的3种亚热带典型次生林地,按10cm一层采集剖面土壤,采用不同方法提取测定土壤DOC和WSOC含量,分析与土壤理化指标的相关性及方法间的显著性关系。结果表明:①典型森林土壤DOC或WSOC含量随土壤剖面深度的增加,呈显著下降趋势。培养离心提取测得的土壤DOC含量明显较低,仅0.82～9.52 mg/kg,超纯水浸提的风干土WSOC含量达10.56～249.19 mg/kg,而0.5 mol/L K₂SO₄提取的鲜土WSOC含量达155.70～576.94 mg/kg,0.5mol/L K₂SO₄浸提的干土WSOC含量最高,达158.94～797.56 mg/kg,含量表现为:DOC<干土超纯水浸提WSOC<鲜土K₂SO₄浸提WSOC<干土K₂...     

Effects of Humic Acids Extracted from Mined Lignite or Composted Vegetable Residues on Plant Growth and Soil Microbial Populations

Growing interest in the market for humic substances with agricultural applications has led to the development of new potential sources of these compounds other than fossil matrices (e.g. different kinds of lignite), which, until now, have represented the main raw material for the extraction of humus-like products. High quality compost (green compost) obtained through the aerobic biostabilization of selected organic residues, such as vegetable waste from source-collection at garden-produce markets, may be considered for this purpose. Beyond the primary need to develop technically and economically reliable procedures for the extraction of humic substances from compost at the industrial scale, importance must be placed on controlling the influence of such compounds on soil-plant systems. Humates from leonardite, representative of the active agents among humus-based commercial preparations, have been compared in pot trials with humic acids, potassium salts, from green compost in order to evaluate their respective effects on soil microbial activity and plant productivity. Differences between pot blocks amended with humic acids have suggested that humus-like substances extracted from compost seem to exert higher stimulative effects on microbial growth and vegetative biomass production than fossil humates.     

Complexation Study of Humic Acids Extracted from Forest and Sahara Soils with Zinc (II) and Cadmium (II) by Differential Pulse Anodic Stripping Voltammetry (DPASV) and Conductimetric Methods

Safranin was used as a model reactive dye for biosorption studies onto various forms of chemically modified biomass of Aspergillus wentii. The experimental equilibrium data was analyzed by various single-, two-, three-, four-, and five-parameter isotherms to understand the biosorption process. Biosorption isotherms modeling shows that the interaction of safranin with A. wentii surface is localized monolayer sorption. Results show that in general the accuracy of models to fit experimental data improves with the degree of freedom. The interaction among adsorbed molecules is repulsive having no association between them and sorption is carried out on energetically different sites and is an endothermic process. The five-parameter Fritz?CSchluender model gives the most accurate fit with high regression coefficients (0.9902?C0.9941), low standard errors (0.0389?C0.0758), and sum of squares error (0.0075?C0.0230) values to all experimental data in comparison to other models. The results disclose that the sorption isotherm models fitted the experimental data in the order: Fritz?CSchluender (five-parameter) > Langmuir > Khan > Fritz?CSchluender (four-parameter) > Temkin. This systematic evaluation of the more important equilibrium isotherm models provided the general basis for making a preliminary selection of an effective model for a given application.     

天津滨海盐碱土地区城市绿地土壤微生物特性研究

对天津滨海盐碱土地区城市绿地土壤微生物特性研究表明不同绿地植物配置模式下0～40cm土壤微生物数量差异极显著,防护林>灌+草>乔木>乔+草>草坪>滨海盐土,0～20cm土层微生物数量是20cm～40cm的3～4倍。在细菌、放线菌和真菌三大类群中,细菌占绝对优势,其次是放线菌和真菌。滨海盐土微生物的季节变化不大,防护林土壤中微生物总数最多时出现在秋季,乔木、乔+草、灌+草、草坪绿地土壤中微生物数量最多时出现在夏季或秋季。细菌、放线菌数量与土壤全盐含量呈显著负相关,细菌的数量与土壤有机质含量呈极显著相关,真菌数量与土壤养分相关不显著.芽孢杆菌的11个种在不同土壤条件和植物配置模式下的生态分布是不同的,最常见的是蜡质芽孢杆菌、拟霉芽孢杆菌、枯草芽孢杆菌、地衣芽孢杆菌和蜂房芽孢杆菌,放线菌主要是链霉属,包括链霉菌属的10大类群,分布最广的类群是灰褐类群、金色类群和青色类群,真菌分布有11个属。在不同植物配置下芽孢杆菌、放线菌和真菌的组成、优势种的组合也存在显著差异。     

不同来源腐殖酸对铜吸附量和吸附机制的研究

本研究从三种供试材料:草炭、褐煤和风化煤中提取腐殖酸,采用NH4OAc和EDTA两种解吸剂,研究三种来源腐殖酸对Cu2+的吸附能力和吸附机制。研究结果表明:三种来源腐殖酸对Cu2+的吸附在吸附量上没有明显差异,但吸附机制却并不完全相同。三种来源腐殖酸对Cu2+的吸附均主要通过离子交换和络合(或螯合)作用,其中,草炭和褐煤提取的腐殖酸的离子交换作用显著大于风化煤提取的腐殖酸,而风化煤提取的腐殖酸的络合(或螯合)作用则明显大于草炭和褐煤提取的腐殖酸。     

Paramagnetic Properties of Humic Substances in Taiga and Tundra Soils of the European Northeast of Russia

The study of paramagnetic activity of humic substances in taiga and tundra soils of the Komi Republic and the assessment of the influence of soil hydromorphism on concentrations of free radicals in the structure of humic acids (HAs) and fulvic acids (FAs) have been performed. The concentration of free radicals in HA specimens was up to 11 times higher than that in FA specimens due to a higher content of aromatic and other condensed structures in HA molecules. This fact attests to the high capacity of HAs to polymerization and complexation reactions with participation of radicals. The average value of g-factor is higher for FA specimens than for HA specimens, which attests to a greater electron density shift of unpaired electron to oxygen atom in the structure of FAs because of its spin-orbital interaction with oxygen-containing functional groups, the concentrations of which are significantly higher in FAs than in HAs. An increase in the concentration of free radicals in the molecular structure of HAs is observed in taiga soils with an increase in the degree of their hydromorphism (from automorphic to semihydromorphic soils), which is related to the biohydrothermal conditions of humus formation in bog-podzolic soils with retarded biochemical processes and low degree of plant litter humification. As a result, HAs with the high content of free radicals in their structure are formed. An opposite situation is observed for HAs in tundra soils with a decrease in the content of unpaired electrons under conditions of the increased hydromorphism. The difference in the character of changes in the paramagnetic activity of HAs in taiga and tundra soils with different degrees of hydromorphism may be related to different natures of plant residues participating in humification processes. A tendency for a decrease in the paramagnetic activity in both HAs and FAs from the south to the north is observed, which may be related to a general decrease in the content of poly-conjugated systems in the structure of humic substances in tundra soils.     

土壤胡敏酸的温和水解及分组研究 Ⅱ.胡敏酸水解产物中的醇类化合物

采用温和水解及薄层层析等分组方法 ,并应用气—质联机技术对土壤胡敏酸 (HA)水解产物中的醇类化合物进行了初步研究。结果表明 :HA水解产物中醇类含量顺序是饱和醇 >甾醇 >非饱和线性醇。饱和醇中主要是C12～ 3 0 中的偶数碳和C15,非饱和线性醇主要是C2 0 -1π、C2 0 -2π和C19-4π。C3 和C4植物条件下形成的HA有一定的差异 ,C3 -HA含有较多的非饱和醇 ,而C4-HA含有更多的饱和醇特别是C12 和C2 6。     

Characteristics of Humic Substances in Paddy Soils

In the present paper,the composition of humus and the charateristics of humic acid from seven paddy soils were compared with those of upland (and/or natural) soils.Results show that:(1) in each group of the soil samples for comparison the HA/FA ratio of the humus of a paddy soil,in most cases,was appreciable higher than that of adjacent upland(and/or natural) soil derived from the same parent material;(2) the humic acid extracted from the paddy soils was characterized by a higher C/O ratio,a higher content of methoxyl groups,and a lower content of carboxyl groups than those from the corresponding upland (and/or natural) flooded soils,implying that the humic acid formed under rice cultivation is in a lower degree of humification than that formed under upland(and/or natural) conditions;and (3) the humic acid of paddy soils,however,was not always characterized by a lower aromaticity than that of the corresponding upland(and/or natural) soils.     

不同来源腐殖酸的组成和性质的研究

本研究从三种有机物料草炭、褐煤、风化煤中提取腐殖酸,对其组成和性质进行了测定,同时对胡敏酸进行酒精沉淀分级。研究结果表明:褐煤胡敏酸氧化度和芳香度最高,其次为风化煤胡敏酸,最后是草炭胡敏酸;风化煤富里酸的氧化度和芳香度最高,其次为褐煤富里酸和草炭富里酸。胡敏酸各级分的回收率均随着级分数的升高而增加。回收率以风化煤胡敏酸最高,依次为褐煤胡敏酸、草炭胡敏酸。     

Sequentially Extracted Arsenic from Different Size Fractions of Contaminated Soils

Five soils from Austria that have high contents of arsenic (As)due to anthropogenic and/or geogenic sources were separated intosand, silt, and clay fractions. The distribution of As among theparticle-size fractions was clay >> silt > sand. Theparticle-size fractions were analysed according to an 8-stepsequential extraction procedure (SEP) designed to assess theprimary reservoirs and extractability of As. Steps 1 and 2,(i.e. NH₄NO₃ and (NH₄)₂SO₄) extractedthe least As, while considerably greater amounts were extractedin steps 3, 4 and 5 (i.e. NH₄H₂PO₄,NH₂OH-HCl, and NH₄F). The greatest amounts of As wereextracted in steps 6 and 7, both NH₄-oxalate extractantstargeting the amorphous and crystalline oxide fractions. Theresidual fraction (step 8) was typically low. The extraction ofthe clays contained generally more As in steps 3 to 8, while Asrelease in the first two steps was typically highest in the sandand silt fractions. These findings are in accord with factoranalysis indicating that the extractants of the SEP areseparated into weak (steps 1 and 2) and strong (steps 3 to 8)extractants. SEP data along with microprobe analyses (X-raymicroanalyses) indicate that most As is associated with Fe andis therefore not readily mobile. Anyhow, As could be releasedupon changes in redox potential or pH. The greaterextractability of As from sand fractions using weak extractantsmay explain the higher toxicity of As in coarse-textured soils,as found in previous studies.     

几种胡敏酸和富里酸分子结构模型的三维可视化与特性研究

针对已提出的几种胡敏酸和富里酸的二维分子结构模型,应用HyperChem软件转换为三维结构并进行几何优化,计算了这些三维模型的能量以及定量构效关系(QSAR)参数。结果表明:几种模型在三维结构和特性上都各不相同,这为从空间角度更直观地认识腐殖物质的分子结构提供了可能性。     

Distribution of Organic Carbon in the Humic Fractions of Diagnostic Horizons from Brazilian Soils

Abstract

This study was developed on 52 soil profiles, 61 surface diagnostic horizons, and 26 subsurface diagnostic horizons classified according to the Soil Taxonomy and Brazilian Soil Classification System (SiBCS) as Mollisols (Chernossolos), Spodosols (Espodossolos), Entisols (Gleissolos), Oxisols (Latossolos), and Histosols (Organossolos). The objective was to quantify the carbon (C) in organic matter fractions and to correlate it with soil chemical attributes. Soil organic matter was fractionated into fulvic acids (C‐FAF), humic acids (C‐HAF), and humin (C‐HUM), and the ratios C‐HAF/C‐FAF and AE (alkaline extract)/C‐HUM were calculated. Humin was the predominant fraction in Mollisols and Oxisols, which showed values of AE/C‐HUM and C‐HAF/C‐FAF lower than 1.0. The humin fraction was also predominant in surface horizons of Spodosols and Entisols, whereas a higher content of C‐FAF and C‐FAH was observed in the subsurface horizons, with values higher than 1.5 for the AE/C‐HUM ratio. C‐HAF was predominant in the Histosols, and C‐HAF/C‐FAF ratio values were higher than 2.0. The highest correlation values with soil attributes were observed for C‐HAF, C‐HUM, and total organic C with pH, sum of bases, and cation exchange capacity. The differences in humic substances distribution was a useful parameter to characterize soil orders in the Brazilian soil classification system and to understand pedogenic processes.     

稻草腐解过程中形成胡敏酸的组成和结构研究

通过稻草腐解实验,采用化学分析方法,研究了稻草腐解过程中土壤胡敏酸的化学特征的动态变化,旨在丰富农作物秸秆还田过程中的胡敏酸化学组成、性质与结构变化的特征。在试验培养条件下,施用稻草后土壤的有机碳含量提高了31.71%,腐殖质含量增加了51.93%,都在90d时达到最大值。施用稻草45d时的PQ值(HA在HS中所占的比例)明显降低,在90d和135d时的PQ值与45d时变化不大。施用稻草后土壤胡敏酸的色调系数(ΔlogK)逐渐减少,相对色度(RF)值迅速增大,胡敏酸的氧化程度和芳构化程度增强。胡敏酸的元素组成以碳为主,含量在52%左右,其次为氧。H/C的比值逐渐降低,O/C的比值不断增大。羧基和酚羟基为主要的酸性基团。羧基含量先降低,后随着腐解的进行,其含量不断升高;酚羟基的含量变化与羧基的含量变化趋势相反;羰基含量逐渐增加。施用稻草会引起紫色水稻土胡敏酸化学组成和结构的变化。     

Humic Acids Derived from Leonardite-Affected Growth and Nutrient Uptake of Corn Seedlings

Using organic fertilizer or soil amendment such as humic substances is an important component for sustainable agriculture. The objective of this study was to determine the effects of different factions of humic acids (HAs) on corn seedling growth and nutrient uptake. The experiment was carried out with both an agar culture in root boxes and a hydroponic culture to which 400 mg/L of different factions of humus acids, mixed HAs, and raw Leonardite were added. The experiments were repeated twice with three replications for each treatment. The results showed that applications of HAs significantly improved the leaf and root growth of corn seedlings compared with the control (no HA addition). In the agar culture, seedlings treated with HAs with relatively low molecular weights had more leaves and twice long of roots compared to control and other treatments. In the hydroponic culture, the mixture of three factions was the best treatment for both shoot and root growth of seedlings.